Thermal Degradation of Kerogen by Hydrous Pyrolysis. A Kinetic Study

Several hydrous pyrolysis kinetic runs have been carried out on a source rock sample from Northern Italy (type II kerogen) under isothermal conditions in the range 260-330°C and at 15-17 MPa in an argon atmosphere. The products have been quantified and grouped into four classes: light (gas + volatile liquids), saturate, aromatic, and heavy (asphaltenes + resins). The distribution of these classes as well as the bulk composition of the overall product was found to be fairly constant during the whole reaction course, suggesting that primary cracking prevails in the temperature range explored. The kinetic results have been interpreted regarding the degradation as the result of numerous simultaneous independent first-order reactions. The number, the relative importance and the Arrhenius parameters for such reactions have been evaluated using an optimization procedure. The best fitting of the experimental data was achieved considering three simultaneous reactions.